Apparatus and method for venting gas from a liquid

Abstract

The present invention relates to an apparatus and method for venting a gas from a liquid, which are applicable to a wide variety of medical liquid delivery systems. The apparatus includes level detectors, a clamp, and a control apparatus operably connected to the level detectors and the clamp. The method includes detecting whether liquid or gas is present at the level detectors, and opening and closing a clamp to vent gas.

What is claimed is: 
     
         1 . An apparatus for venting gas contained in a liquid flowing in a liquid flow circuit comprising:
 a) a gas collection chamber located within the liquid flow circuit so that liquid flows through the gas collection chamber allowing gas to separate from the liquid and establish a gas-liquid interface within the gas collection chamber;   b) a gas vent chamber at the top of the gas collection chamber through which gas within the gas collection chamber can be released;   c) a lower detector located in either the gas collection chamber or the gas vent chamber, and an upper detector located in either the gas collection chamber or the gas vent chamber, said lower detector located below said upper detector, and said lower and upper detectors being capable of detecting gas or liquid;   d) a clamp located in said gas vent chamber either between the lower and the upper level detectors or above both level detectors; and   e) a control apparatus for opening and closing the clamp in response to whether the lower and upper detectors detect gas or liquid within the gas collection chamber.   
     
     
         2 . The apparatus of  claim 1 , wherein the liquid is blood. 
     
     
         3 . The apparatus of  claim 2 , wherein the clamp is a pinch clamp. 
     
     
         4 . The apparatus of  claim 2 , wherein the clamp is a balloon clamp. 
     
     
         5 . The apparatus of  claim 2 , wherein the lower level detector can detect density. 
     
     
         6 . The apparatus of  claim 5 , wherein the upper level detector can detect density. 
     
     
         7 . The apparatus of  claim 6 , wherein the apparatus is a cassette. 
     
     
         8 . The apparatus of  claim 1 , wherein the gas collection chamber and the gas vent chamber are a single unit. 
     
     
         9 . A method for venting gas contained in a liquid flowing in a liquid flow circuit comprising:
 flowing the liquid into a gas collection chamber located within the liquid flow circuit so that liquid flows through the gas collection chamber allowing gas to separate from the liquid and establish a gas-liquid interface within the gas collection chamber;   detecting whether liquid is present at a lower position in either the gas collection chamber or a gas vent chamber by a lower level detector;   opening a clamp if a liquid is not present at the lower position;   detecting whether liquid is present at an upper position in either the gas collection chamber or the gas vent chamber by an upper level detector; and   closing the clamp if liquid is present at the upper position.   
     
     
         10 . An extracorporeal hemodialysis circuit comprising:
 a) arterial tubing for receiving unfiltered blood from a patient;   b) venous tubing for providing filtered blood to a patient; and   c) a dialyzer and an apparatus for venting gas according to  claim 1  located within the extracorporeal hemodialysis circuit so that blood flows from the patient, through the arterial tubing, through the dialyzer, through the apparatus for venting gas according to  claim 1 , and towards the venous tubing.